In a split decision based exclusively on the intrinsic evidence, the U.S. Court of Appeals for the Federal Circuit held, inter alia, that the claim term "therapeutically effective amount" in one patent did not limit the claim to products effective in curing disease and remanded to determine whether a prior art reference anticipated the claim. Amgen Inc. v. Hoechst Marion Roussel, Inc., Case No. 05-1157 (Fed. Cir. Aug. 3, 2006) (Schall, J.; Michel, C.J., dissenting in part).
Amgen is the owner of five U.S. patents directed to recombinant deoxyribonucleic acid (DNA) technology relating to the production of the hormone erythropoietin (EPO). All five patents share a common specification and descend from a single parent application. In 1997, Amgen brought a declaratory judgment action against Hoechst Marion Roussel, Inc. (now known as Aventis Pharmaceuticals Inc.) (HMR) and Transkaryotic Therapies, Inc. (TKT) (collectively, HMR/TKT) in the United States District Court for the District of Massachusetts, alleging that HMR/TKT'’s Investigational New Drug Application for an EPO product infringed the five patents. This case was back for the second time before the Court following proceedings on remand in which the district court construed the term "therapeutically effective amount" recited in one of the asserted patents’ claims and conducted a further bench trial.
On appeal, the panel majority considered intrinsic evidence only and relied almost exclusively on the patent specification, which indicates that the claimed invention is used in "therapy" to produce "any or all" of the following "effects": stimulation of reticulocyte response, development of ferrokinetic effects, erythrocyte mass changes, stimulation of hemoglobin and increasing hematocrit levels. Based on this language, the panel majority concluded that increasing hematocrit is only one of the biological effects produced by the claimed invention and agreed with HMR/TKT that the district court misinterpreted this passage when it read it as limiting the claimed invention to products with "any or all" of the first four listed effects ascribed in vivo to EPO and also an increase in hematocrit. Concluding that the claim term "therapeutically effective amount" did not limit the claim to products effective in curing disease, the Court remanded the case to determine whether a prior art reference anticipated the claim.
Application of the doctrine of equivalents post-Festo was another dominant theme in this case. Here, the Court held that the district court erred in ruling that Amgen rebutted the presumption that, during prosecution, it surrendered coverage to EPO with a 165-amino acid sequence, which is the sequence of HMR/TKT’s product. The Court concluded that the amendment at issue, "EPO having the complete amino acid sequence shown in Figure 6," which depicted a 166-amino acid sequence, may have been central to overcoming a double patenting rejection and, therefore, was likely more than tangentially related to the 165-amino acid equivalent.
In his dissenting opinion, Michel said he did not agree with the revised construction of "therapeutically effective." The chief judge also voiced his frustration at the prolonging of this high-profile patent case, lamenting "[w]hen will it end? Ironically, the patents in dispute may expire before this litigation concludes."
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